Liquid Waste Decomposition by DC Water Plasmas at Atmospheric Pressure

Abstract

Decomposition system of liquid waste by DC water plasmas generated at atmospheric pressure was developed. The developed water plasma torch is a DC thermal plasma generator of coaxial design with a cathode of hafnium embedded into the copper rod and a nozzle-type copper anode. The plasma torch can generate 1 00%-steam plasma without a commercially available steam generator. The water plasma system is a portable light-weight system that does not require any gas supply. The plasma system has high energy-efficiency since cooling water is not needed. Methanol or ethanol used as model substances of liquid waste was mixed with water for plasma supporting gas. Rapid and complete decomposition for these alcohols produce H 2 , CO, and C0 2 in the decomposed gas. The decomposition rate as well as the decomposition mechanism was determined by gas chromatography and mass spectrometry. The water plasma system can be used for industrial application of liquid waste decomposition.

DC Water Plasma at Atmospheric Pressure for the Treatment of Aqueous Phenol

“…Recently, there has been growing interest in studying thermal plasma technology for hazardous waste treatment due to its high energy densities and high temperatures, oxidation, and reduction atmosphere in accordance with required chemical reaction, and rapid quenching rate (10 5 −10 6 K s −1 ) , . Watanabe et al have developed an innovative direct current (DC) water plasma technique for the decomposition of gaseous and liquid wastes, such as hydrofluorocarbons (HFCs) − and organic solvents , . As reported previously, the destructive efficiency of HFC-134a and PCB would be achieved as high as 99% for the feed rate of 1.3−37 kg h −1 and 100 kg h −1 , respectively.…”